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Listening for Electromagnetic Fields in wild spaces

post by Sam Street
March 2021 – June 2021

In researching various audio recording techniques for Branching Songs, particularly those able to record inaudible frequencies and fields, we turned our attention to electromagnetic field listening with the help of an Electrosluch (DIY Circuit Kit generously provided by Giorgio Magnanensi of Vancouver New Music). This simple device allows one to listen to and record the myriad electromagnetic fields and disturbances which now penetrate even the most remote corners of our planet. As any movement of electricity creates such a field, sounds detected can range from ambient radio waves to household appliances, or high electric voltage (some “ghost hunters” use similar listening devices to detect “anomalous” disturbances in the local electromagnetic fields), and even the sound of radio being tuned by trees. This post will detail the initial test performed by research assistant Sam Street at Trout Lake Park.

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A close up view of the electrosluch. Photo by Keira Madsen.

set up and site

For the recording setup, the Electrosluch’s 3.5mm stereo output was run to a MixPre3 recorder, stored in a cross-body bag, leaving the hands free for using the device. While there are no controls beyond a simple on/off switch, the instrument’s “listening field” is very directional, due to how its two inductors receive and interact with the surrounding electromagnetic fields (EMFs for short). This means that the user can effectively “dowse” their surroundings in search of fields and their resultant sounds. With one’s listening restricted to over-the-ear headphones, the mobile use of the Electrosluch provides a new way of navigating space according to unseen but pervasive forces.

Starting south of Trout Lake, the test began next to the Skytrain tracks and transformer station, themselves thrumming with energy. Here, and in the local residential area, the main buzzing sound heard is created by the 60hz frequency of alternating current electricity, though each house, power line, or appliance created its own varied harmonics above the fundamental. This sound was fairly constant all the way up to the edge of the park, where it predictably tapered off.


Julie holding the electrosluch by a pre-amp to pick up its electromagnetic field. Photo by Keira Madsen.

EMF from trees

In the park surrounding Trout Lake, EMFs were more scarce. Coming out of being bathed with fields and sounds, the somewhat more “natural” (or at least, less electronic) space of the park was a field of silence populated by small zones and directional flows of sound. Through walking and listening, an intuitive technique was used; constantly changing the direction, orientation, and height of the device to search out the ambient fields—a kind of electromagnetic dowsing. In underground cables there are blips of data being fired, across fields there would be directional hums, and if held aloft the Electrosluch could detect commercial radio waves, though fairly scrambled. One of the more noteworthy discoveries was that when “listened to” up-close with the device, radio waves could be heard clearly through nearly every tree in the park. It can only be assumed that their tall bodies and conductive flesh act as antennae.

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The electrosluch in its case. Photo by Keira Madsen.

a new field of listening

From a subjective point of view, EMF listening provided a truly novel way of navigating an invisible space that I had considered, but never been able to experience so viscerally. I would walk cautiously, probing every direction and stopping to listen, to tease out faint sounds. The quality of sounds was really so varied that I wanted to listen and experiment with everything, and each possible object before me. Disappointingly, the range of the Electrosluch was not great enough to pick up anything from a jet liner passing overhead.

After the park, the test moved back south into residential areas again and up to the Skytrain line to wait under the overhead tracks. After waiting five minutes, listening to the hum of the tracks, there came an eerie whistling. The train passed with an electric commotion, loud and strong, rhythmic with the passing cars. Its wake left a ghostly,  almost vocal tone. Spurred on by these results, I followed the tracks east to where I knew they met the ground, and I waited alongside the tracks. Catching four passes in total, and even a train pulling to a stop before me, the trains sang.

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